With the exponential rise in the quantity of data and restrictions imposed by government regulations, so grow the continuous demands by companies in searching for data storage means with a higher capacity and efficiency. Conventional Small Computer System Interface (SCSI) has encountered a bottleneck. To resolve this issue, storage device manufacturers re-evaluated existing storage device structures and started experimenting with new serial technologies to improve storage efficiency in enterprise server systems.
The current high speed serial technologies used in the enterprise server market can be generally categorized into two types, namely Fiber Channel and iSCSI. Fiber Channel is a gigabit speed serial technology standardized in the T11 Technical Committee of the InterNational Committee for Information Technology Standards (INCITS), an American National Standard Institute (ANSI) accredited standards committee. It is mostly implemented on fiber optic cables but can also run on twisted-pair copper wire or coaxial wire. Fiber Channel Protocol (FCP) is commonly known as the next generation SCSI protocol as it employs the SCSI transmission protocol in a fiber channel environment. On the other hand, iSCSI implements the SCSI transmission protocol in an Internet Protocol (IP) environment and transmits data over TCP/IP networks, resulting in a communication protocol standard of its own. The advantage of iSCSI is that with IP as the medium, it goes beyond the limitation in distance associated with traditional SCSI. In addition, it accommodates the existing IP network in an enterprise user's Information Technology (IT) environment and has the same structure of data access as in a current Fiber Channel Storage Area Network (FC-SAN). In fact, the difference between traditional FCP and iSCSI is the medium carrying the protocol. Both put emphasis on the concept of SAN. Therefore, the type of storage device used in the storage network will not be affected by the protocol implemented, be it iSCSI or FCP, both adapt high spin rate optical drives or SATA hard drives. The only noticeable differentiation lies in the efficiency disparity between the iSCSI and FCP protocols. From a host system's perspective, both iSCSI and FCP storage devices communicate to it via standardized Logic Unit Numbers (LUN). In other words, for storage device manufacturers, the interface to and iSCSI or FCP usually allows interoperability with affecting data accessibility.
In existing double backup server structures, the host interface to the disk array typically adopts iSCSI or Fiber Channel with a bandwidth reaching 2 Giga Byte (GB) or 4 GB. This means that the amount of data transfer has increased tremendously. However, the current known connection among disk arrays still employs Giga Byte Ethernet (GbE) protocol for cache mirroring. The 1 Gb bandwidth provided by GbE apparently can not handle the 2 GB or 4 GB data transfer required by the host interface, resulting in a starvation of storage efficiency in a double backup server structure.